The present invention relates to an oil and air lubrication device which distributes an oil to a plurality of lubrication points through a plurality of branch passages as the oil is sent by air from an oil source along the peripheral surface of a single oil feed passage line.
Oil and air lubrication has advantages that the required quantity of an oil is less than that in oil mist lubrication, and the oil does not leak and contaminate the environment. For example, the oil and air lubrication is performed to send the oil to lubrication points at the trains of a multi-train bearing such as the roll end portion support bearing of a rolling machine. For that purpose, a single oil feed passage line having oil feed passages gradually different from each other in diameter depending on the number of the lubrication points is provided to send the oil from the oil feed passages to the lubrication points through branch passages extending in the radial directions of the oil feed passages, as described in the Japan Patent Application (OPI) No. 123657/88 (the term "OPI" as used herein means an "unexamined published application").
The rolling machine requires a lubricating oil of high viscosity. However, if such an oil of high viscosity is used in the above-described conventional manner of performing the oil and air lubrication to send the oil to the lubrication points, the oil being send along the peripheral surface of the oil feed passage line does not uniformly flow into the branch passages. For that reason, the lubrication is not performed enough at some lubrication point. Therefore, the conventional manner of performing the oil and air lubrication to send the oil to the lubrication points cannot be adopted for the roll end portion support bearing of the rolling machine, but oil feed passage lines need to be separately provided for the lubrication points, respectively, to send the oil thereto. This results in generating a complicated passage construction, and increasing the cost of processing therefor.
A distribution unit 50, which is shown in FIGS. 12 and 13 and sends appropriate quantities of an oil to a plurality of lubrication points and passes the rest of the oil to a next plurality of lubrication points as the oil is sent through a single oil feed passage line, was disclosed in the European Patent Publication No. 0 010 269 B1. After the oil is sent into the distribution unit 50 through an inflow passage 51, the oil flows into a large number (ten) intermediate passages 53a, 53b, 53c, 53d, 53e, 54a, 54b, 54c, 54d and 54e opened into the circumferentially spaced portions of the peripheral surface of a passage 52 communicating with the inflow passage. The oil having flowed into the five intermediate passages 53a, 53b, 53c, 53d and 53e undergoes confluence in a confluence passage 55, and is then sent out to the next lubrication points through an outflow passage 56. The oil having flowed into the other five intermediate passages 54a, 54b, 54c, 54d and 54e enters into a confluence passage 58 through an annular passage 57 so as to undergo confluence, and is then sent out to the former lubrication points. The oil and air for sending the oil tend to be larger in quantities on the lower portions of the peripheral surfaces of the inflow passage 51 and the passage 52 than on the upper portions thereof due to gravity. However, the oil and the air can be distributed nearly in a desired manner by the unit 50, regardless of the tendency, because the intermediate passages 53a, 53b, 53c, 53d, 53e, 54a, 54b, 54c, 54d and 54e are distributively opened into the circumferentially spaced portions of the peripheral surface of the passage 52. Although the distribution unit 50 is thus designed not to be adversely affected by gravity, it is troublesome and complicated to perform processing to form the many intermediate passages and the annular passage 57, and it is therefore difficult to manufacture the unit. Besides, if the diameter of each of the intermediate passages is made small, the passage is more likely to be clogged. If the diameter is made large, the entire size of the distribution unit 50 is enlarged.